Fix unnecessarily added undo steps when deleting only scene

Steps to reproduce were: startup.blend, move any object, delete active scene (nothing happens), undo (nothing happens), second undo is needed to revert object transformation

4 files changed, 32 insertions, 12 deletions

diff --git a/source/blender/editors/include/ED_screen.h b/source/blender/editors/include/ED_screen.h
index c8f123992a1..6ffe005ca1a 100644
--- a/source/blender/editors/include/ED_screen.h
+++ b/source/blender/editors/include/ED_screen.h
@@ -105,7 +105,7 @@ bScreen *ED_screen_add(struct wmWindow *win, struct Scene *scene, const char *na
 void    ED_screen_set(struct bContext *C, struct bScreen *sc);
 void    ED_screen_delete(struct bContext *C, struct bScreen *sc);
 void    ED_screen_set_scene(struct bContext *C, struct bScreen *screen, struct Scene *scene);
-void    ED_screen_delete_scene(struct bContext *C, struct Scene *scene);
+bool    ED_screen_delete_scene(struct bContext *C, struct Scene *scene);
 void    ED_screen_set_subwinactive(struct bContext *C, struct wmEvent *event);
 void    ED_screen_exit(struct bContext *C, struct wmWindow *window, struct bScreen *screen);
 void    ED_screen_animation_timer(struct bContext *C, int redraws, int refresh, int sync, int enable);
diff --git a/source/blender/editors/screen/screen_edit.c b/source/blender/editors/screen/screen_edit.c
index ae0d2619645..b714eb00169 100644
--- a/source/blender/editors/screen/screen_edit.c
+++ b/source/blender/editors/screen/screen_edit.c
@@ -1707,8 +1707,11 @@ void ED_screen_set_scene(bContext *C, bScreen *screen, Scene *scene)
 	
 }
 
-/* only call outside of area/region loops */
-void ED_screen_delete_scene(bContext *C, Scene *scene)
+/**
+ * \note Only call outside of area/region loops
+ * \return true if successful
+ */
+bool ED_screen_delete_scene(bContext *C, Scene *scene)
 {
 	Main *bmain = CTX_data_main(C);
 	Scene *newscene;
@@ -1718,11 +1721,13 @@ void ED_screen_delete_scene(bContext *C, Scene *scene)
 	else if (scene->id.next)
 		newscene = scene->id.next;
 	else
-		return;
+		return false;
 
 	ED_screen_set_scene(C, CTX_wm_screen(C), newscene);
 
 	BKE_scene_unlink(bmain, scene, newscene);
+
+	return true;
 }
 
 ScrArea *ED_screen_full_newspace(bContext *C, ScrArea *sa, int type)
diff --git a/source/blender/editors/screen/screen_ops.c b/source/blender/editors/screen/screen_ops.c
index 1d31cc04e38..1309fb103e9 100644
--- a/source/blender/editors/screen/screen_ops.c
+++ b/source/blender/editors/screen/screen_ops.c
@@ -3986,7 +3986,9 @@ static int scene_delete_exec(bContext *C, wmOperator *UNUSED(op))
 {
 	Scene *scene = CTX_data_scene(C);
 
-	ED_screen_delete_scene(C, scene);
+	if (ED_screen_delete_scene(C, scene) == false) {
+		return OPERATOR_CANCELLED;
+	}
 
 	if (G.debug & G_DEBUG)
 		printf("scene delete %p\n", scene);
diff --git a/source/blender/editors/space_outliner/outliner_tools.c b/source/blender/editors/space_outliner/outliner_tools.c
index 27100aac8cf..50171d7f032 100644
--- a/source/blender/editors/space_outliner/outliner_tools.c
+++ b/source/blender/editors/space_outliner/outliner_tools.c
@@ -273,29 +273,40 @@ static EnumPropertyItem prop_scene_op_types[] = {
 	{0, NULL, 0, NULL, NULL}
 };
 
-static void outliner_do_scene_operation(
+static bool outliner_do_scene_operation(
         bContext *C, eOutliner_PropSceneOps event, ListBase *lb,
-        void (*operation_cb)(bContext *, eOutliner_PropSceneOps, TreeElement *, TreeStoreElem *))
+        bool (*operation_cb)(bContext *, eOutliner_PropSceneOps, TreeElement *, TreeStoreElem *))
 {
 	TreeElement *te;
 	TreeStoreElem *tselem;
+	bool success = false;
 
 	for (te = lb->first; te; te = te->next) {
 		tselem = TREESTORE(te);
 		if (tselem->flag & TSE_SELECTED) {
-			operation_cb(C, event, te, tselem);
+			if (operation_cb(C, event, te, tselem)) {
+				success = true;
+			}
 		}
 	}
+
+	return success;
 }
 
-static void scene_cb(bContext *C, eOutliner_PropSceneOps event, TreeElement *UNUSED(te), TreeStoreElem *tselem)
+static bool scene_cb(bContext *C, eOutliner_PropSceneOps event, TreeElement *UNUSED(te), TreeStoreElem *tselem)
 {
 	Scene *scene = (Scene *)tselem->id;
 
 	if (event == OL_SCENE_OP_DELETE) {
-		ED_screen_delete_scene(C, scene);
-		WM_event_add_notifier(C, NC_SCENE | NA_REMOVED, scene);
+		if (ED_screen_delete_scene(C, scene)) {
+			WM_event_add_notifier(C, NC_SCENE | NA_REMOVED, scene);
+		}
+		else {
+			return false;
+		}
 	}
+
+	return true;
 }
 
 static int outliner_scene_operation_exec(bContext *C, wmOperator *op)
@@ -303,7 +314,9 @@ static int outliner_scene_operation_exec(bContext *C, wmOperator *op)
 	SpaceOops *soops = CTX_wm_space_outliner(C);
 	const eOutliner_PropSceneOps event = RNA_enum_get(op->ptr, "type");
 
-	outliner_do_scene_operation(C, event, &soops->tree, scene_cb);
+	if (outliner_do_scene_operation(C, event, &soops->tree, scene_cb) == false) {
+		return OPERATOR_CANCELLED;
+	}
 
 	if (event == OL_SCENE_OP_DELETE) {
 		outliner_cleanup_tree(soops);